The electric utility sector accounted for nearly 50 percent of total renewable energy consumption in 1994 (Table 2). The industrial/nonutility sector accounted for 40 percent, followed by the residential and commercial sector with 10 percent. Consumption in each sector is dominated heavily by a single renewable energy source.
Other than hydroelectric power and electricity generation from wood and wood wastes, no renewable energy resource provided a significant portion of U.S. electric power before the 1970s. In 1970, U.S. renewable electricity generation capacity totaled about 63,000 megawatts, almost 18 percent of U.S. total generation capacity.(2) Of that total, however, more than 61,000 megawatts were accounted for by conventional hydroelectric power. Roughly another 1,000 megawatts were accounted for by wood and wood waste facilities. The remainder is distributed among the other renewable energy resources.
Since 1990, renewable energy consumption has grown at an annualized rate of 0.8 percent, compared with 1.2-percent annual growth in total energy consumption (Figure 2). All sources of renewable energy consumption have grown, except for hydroelectric power, which is highly dependent on precipitation levels, so its lack of growth should not be viewed as part of any long-term trend.
The largest source of renewable energy is hydroelectric power (Table 1), which is used almost exclusively (about 95 percent) in the electric utility sector (Table 2). The remainder is consumed by industrial facilities that operate their own hydroelectric generators (usually ■run-of-the-river■ units). It is important to note that the term ■industrial/nonutility■ is used in this publication to reflect the inclusion of independent power producers as well as cogeneration operations of grid-connected and non-grid-connected facilities.
In contrast, biomass is used largely to produce heat for use in the residential, industrial, and nonutility sectors. The industrial and nonutility sectors accounted for more than 75 percent of total biomass energy consumption in 1994. About 75 percent of the biomass used for energy by industries was for ■process heat■ used to make products such as bricks and paper. The major source of industrial and nonutility biomass energy was black liquor (a pulpwood by- product waste fuel), roundwood fuelwood, and residues from primary and secondary wood mills. Wood-burning in the residential sector accounted for about 20 percent of total biomass energy consumption in 1994; a small amount of energy (0.04 quadrillion Btu) was derived from wood-burning in the commercial sector. Biomass in the form of alcohol fuels is the only renewable energy used in any measurable amount in the transportation sector.
Geothermal energy has three applications: electricity production or generation, low-temperature process heat (e.g., for crop drying), and heating and cooling applications for buildings. The data shown in this report, however, represent only geothermal energy used to generate electricity. EIA does not collect consumption information on geothermal energy used for low- temperature process heat or geothermal (groundwater) heat pumps. Of the geothermal energy devoted to electricity production, nearly 60 percent is used by the industrial sector (Table 2).
Virtually all wind energy consumption and all growth in solar energy consumption since 1990 has been for power production in the industrial and nonutility sectors. Small-scale solar energy devices in the residential and commercial sectors have remained flat at0.06 quadrillion Btu since 1990, while industrial solar energy consumption has increased slightly, from 7 trillion Btu in 1990 to 8 trillion Btu in 1994. Wind energy consumption has grown steadily at a 10.7-percent annualized rate since 1990, reflecting the after-tax economic viability of wind energy in appropriate locations.
Electricity generation consumed an estimated 4 quadrillion Btu of renewable energy in 1994 (Table 3), 63 percent of which came from conventional hydroelectric generation in the electric utility sector. Generation from biomass in all sectors accounted for another 15 percent, net imports of electricity from renewable energy accounted for 9 percent, and domestic generation from geothermal energy contributed another 9 percent.
While renewable energy consumption for electricity generation in the utility sector has declined at a 3.5-percent annual rate over the past 4 years, industrial sector generation has increased steadily. Since 1990, industrial and nonutility consumption of geothermal-based electricity has increased by 10 percent per year, with their use of electricity from biomass increasing by 7 percent per year.
Renewable energy contributed 375 billion kilowatthours, or 11 percent, of the Nation's estimated 3,286 billion kilowatthours (3) of net electricity generation in 1994 (Table 4).(4) The electric utility sector provided 68 percent of renewable-based electricity and the nonutility sector 23 percent. Net imports accounted for the remaining 9 percent.
U.S. renewable generating capacity totaled 95 thousand megawatts in 1994 (Table 5). Of this, 83 percent was hydroelectric, followed by biomass (12 percent) and geothermal (3 percent).
Note that the capacity and generation totals for wind and solar do not always increase or decrease proportionately from year to year. Two factors may contribute to this phenomenon: